Barcelona forward Lionel Messi was carried off on a stretcher during his side's Champions League match on Thursday morning (AEDT), but his knee injury is not as bad as first feared.

The Nou Camp held its breathe when the reigning World Player of the Year collapsed to the ground clutching his left knee after colliding with Benfica goalkeeper Artur and looked to be in severe discomfort as he was taken from the pitch.

Barcelona released a statement after the game saying the Argentine star suffered bruising to his knee.

"Tests carried out tonight have confirmed that the player has a bruising of the bone on the outside of the left knee," a club statement read.

"The rate of his recovery will determine whether he will be available for the next game, on Sunday against Real Betis."

Messi has three matches left in 2012 to score the two goals he needs to beat Gerd Muller's record of 85 goals in a calendar year set in 1972.

The little maestro has scored 28 goals already this season, following up his record-breaking 73 goals last term, helping Barcelona achieve the best ever start to a la Liga season, winning 13 and drawing one of its first 14 matches, despite losing coach Pep Guardiola in the summer.

The draw meant Benfica was forced to settle for a place in the Europa League, while Celtic went goes through to the last 16 courtesy of a 2-1 victory over Spartak Moscow.

The match was of little significance to Barcelona who had already secured top spot in Group G.

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